1. Field of the Invention
The invention relates to a colorimetric measurement head for determining the internal color of a non-opaque material, in particular the internal color of the human skin.
2. Description of the Related Art
Until now, the appearance of materials has been assessed with optical measurement apparatuses essentially making it possible to study the reflecting properties of the surface of these materials.
FR-A-2,650,890 relates to an optical apparatus intended to make it possible to evaluate the brilliance of a surface. This relatively complex apparatus involves polarizer and analyser filters. In addition, the measurement is carried out by eliminating the internal color component.
In all these optical devices, the light fluxes coming from the surface of the material to be studied are predictably good. These optical devices are therefore very useful for studying opaque surfaces.
In nature or in industry, however, objects exist which consist of materials which are complex from an optical point of view because at the same time, to a greater or lesser extent, they are transparent, selectively absorbent, scatter and are heterogeneous.
For such non-opaque materials, the information supplied by conventional optical measurement apparatuses does not allow the materials to be classified properly. In particular, these conventional measurement devices can give similar information, for two non-opaque materials of very different visual appearance, which does not make it possible to draw a distinction between the two materials.